Wireless industrial process monitor

ABSTRACT

An industrial process monitor for monitoring an industrial process includes a controller configured to control operation of the industrial process monitor. An ambient environment sensor is configured to sense an ambient environment of the industrial process proximate the device and responsively provide a sensor output signal. Output circuitry is configured to provide an output based upon the sensor output signal. The controller causes the ambient environment sensor to enter a high power mode upon detection of an anomaly and/or probable anomaly in the sensor output signal.

BACKGROUND

The present invention relates to industrial process control ormonitoring systems. More specifically, the present invention relates towireless process field devices used in such systems.

In industrial settings, systems are used to monitor and controlinventories and operation of industrial and chemical processes, and thelike. Typically, the system that performs these functions uses fielddevices distributed at key locations in the industrial process coupledto control circuitry in the control room by a process control loop. Theterm “field device” refers to any device that performs a function in adistributed control or process monitoring system, including all devicesused in the measurement, control and monitoring of industrial processes.

Typically, each field device also includes communication circuitry thatis used for communicating with a process controller, other fielddevices, or other circuitry, over the process control loop. In someinstallations, the process control loop is also used to deliver aregulated current and/or voltage to the field device for powering thefield device. The process control loop also carries data, either in ananalog or digital format.

In some installations, wireless technologies have begun to be used tocommunicate with field devices. Wireless operation simplifies fielddevice wiring and setup. Wireless installations are currently used inwhich the field device includes an internal power source. However,because of power limitations, the functionality of such devices istypically limited.

Typically, field devices are used to sense or control process variablesin an industrial process. However, in some installations, it may bedesirable to monitor the local environment of the field device.

SUMMARY

An industrial process monitor for monitoring an industrial processincludes a controller configured to control operation of the industrialprocess monitor. An ambient environment sensor is configured to sense anambient environment of the industrial process proximate the device andresponsively provide a sensor output signal. Output circuitry isconfigured to provide an output based upon the sensor output signal. Thecontroller causes the ambient environment sensor to enter a high powermode upon detection of an anomaly and/or probable anomaly in the sensoroutput signal.

This Summary and the Abstract are provided to introduce a selection ofconcepts in a simplified form that are further described below in theDetailed Description. The Summary and the Abstract are not intended toidentify key features or essential features of the claimed subjectmatter, nor are they intended to be used as an aid in determining thescope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram showing a process control ormonitoring system for use with the present invention.

FIG. 2 is a block diagram showing components in a field device of oneembodiment of the present invention.

FIG. 3 is a more detailed block diagram showing components of the fielddevice of FIG. 2.

FIG. 4 shows a captured image of an industrial process during low power,low resolution “pilot mode” operation.

FIG. 5 is an image collected of the industrial process in a low power,low resolution pilot mode of operation showing an anomaly in the image.

FIG. 6 is an image captured of industrial process in a high power, highresolution mode of operation.

FIG. 7 is a graph showing the frequency domain of a captured acousticsignal during a low power, low spectral resolution pilot mode ofoperation.

FIG. 8 is a graph of the frequency domain of captured acoustic dataduring a high power, high spectral resolution mode of operation.

FIG. 9 is a graph of amplitude versus frequency illustrating a boundaryfence.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Many high value monitoring applications which use monitoring techniquessuch as video, infrared, ultrasonic and audio require systems that canacquire information at high sampling rates and/or high resolutions. Forexample, a low resolution infrared monitoring system may be capable ofmonitoring an overall thermal profile. However, in order to specificallyidentify a location of a thermal anomaly high resolution is required.The capture and analysis of high resolution infrared images is needed tofully characterize the anomaly and to distinguish it from backgroundnoise or from expected thermal changes in the environment. However, theacquisition and processing of such high resolution images requiressignificant power. This quickly depletes the batteries of a self-poweredfield device such as a wireless field device. A similar problem existswith other techniques for monitoring an ambient environment, or example,audio and ultrasonic monitoring. In order to correctly characterize anacoustic event, high sampling rates are needed in order to analyze thespectral content so that a signal profile can be compared to a knownacoustic signature, for example one which occurs when a system leaks.

The present invention offers techniques for addressing the aboveproblem. A system is provided for monitoring the ambient environmentwhich utilizes both a low power mode that is capable of acquiring dataat low resolutions and/or sampling rates, and a high power mode that isonly activated when the low power (pilot) mode detects a signal ofpotential interest. The present invention provides a technique formonitoring the ambient environment of an industrial process and relatesto monitoring systems implemented in locally or internally poweredwireless field devices. A wireless industrial process monitor isimplemented in a field device and is configured to monitor an ambientenvironment in the industrial process. The monitoring may be through anyappropriate ambient environment sensor including video, infrared,acoustic, or other. Such a sensor requires a high sampling frequencyand/or high resolution in order to characterize and locate events ofinterest in the local (ambient) environment and to distinguish sensedsignals related to these events from background noise. However, as highresolution and/or high sampling frequencies require an increased amountof power, a configuration is used in which a low energy “pilot mode” isimplemented for normal operation. In this “pilot mode”, a low resolutioninitial measurement is obtained. If an anomaly is detected based uponthis low resolution initial measurement, a high resolution, high powermode may be entered by the system. In the high power mode, data iscollected at a high data rate and/or resolution. Subsequently, thedevice may re-enter the “pilot mode” for continued low power operation.

FIG. 1 is a simplified diagram showing an example process control ormonitoring system 10 which includes a control room 12 communicating withfield devices 14 and 16 through a wireless gateway 13. Communicationbetween gateway 13 and control room 12 may be over a wired or wirelesscommunication link. Field device 14 is shown coupled to process piping18 and field device 16 is shown coupled to storage tank 20. However,devices 14, 16 may be located at any desired location. Devices 14 and 16include antennas 22 and 24, respectively, for transmitting and/orreceiving information from antenna 26 associated with wireless gateway13. Devices 14 and 16 communicate using wireless radio frequency (RF)communication links 28, 29 and 30 with each other and with a remotelocation such as gateway 13. One example wireless communication protocolis the WirelessHART® protocol in accordance with IEC 62591. Fielddevices 14 and 16 include components to provide local (internal) powerto the devices without requiring additional wires. For example, device14 and 16 can include solar cells and/or batteries for local power.

As field device 14 and 16 operate using limited power, their processingabilities and the amount of data which they are capable of transmittingis limited. In one aspect, the present invention includes a wirelessfield device such as device 14 and 16, which includes the ability tomonitor the ambient environment using an ambient environment sensor.Wireless field devices which are capable of operating at remotelocations that do not require an external power source are availablefrom, for example, Rosemount Inc. of Chanhassen, Minn. Such devices areconfigured to measure process variables or obtain other processinformation and transmit information using wireless communicationtechniques such as the WirelessHART® protocol.

FIG. 2 is a simplified block diagram showing field device 14 shown inFIG. 1 in greater detail. According to this embodiment, field device 14includes an optional transducer 31, wireless input/output(communication) circuitry 32, controller 34, power supply circuit 36,battery 38 and solar panel 40. The transducer 31 can be either a sensorused to sense a process variable or a control element, such as a valve,which is used to control a process variable. The wireless communicationcircuitry 32 couples to antenna 22 for communication with gateway 13over its antenna 26. Optionally, device 14 communicates directly withcontrol room 12. Power supply circuit 36 is used to provide power tocircuitry within field device 14. The power supply circuitry 36 canoperate using internal power received from solar cell 40 and/or powerreceived from battery 38. The power supply circuitry 36 can be poweredfrom any type of internal power source that does not require wiring to aremote power source. The power supply circuitry 36 can be self-containedwithin the field device 14 or, in some embodiments, be locatedexternally to the field device and positioned proximate to the fielddevice. For example, a solar powered unit can be used to power atransmitter or other field device over a two wire connection which isalso used to carry information. In such a configuration, the powersupply circuitry can also provide wireless communication to a remotelocation. If sufficient power is received from solar cell 40, powersupply circuitry 36 can also be used to charge the battery 38. Anambient environment sensor 74 is used to monitor the environment ofdevice 14 as explained below in more detail.

FIG. 3 is a more detailed block diagram of process field device 14according to an embodiment of the present invention and shows optionaltransducer 31 configured as a process variable sensor which can be usedto measure a process variable such as pressure, temperature, etc. Theprocess variable sensor 31 may be positioned within the housing ofdevice 14 or external to the housing as illustrated in FIG. 3.Measurement circuitry 52 couples to process variable sensor 31 and isused to perform initial signal processing prior to providing ameasurement signal to controller 34. An optional user input 54 is shownin FIG. 3. Similarly, an optional local output device such as LCDdisplay 56 is shown.

Controller 34 is typically a microprocessor based controller and couplesto a memory 60 and a clock 62. The clock 62 determines the operationspeed of digital circuitry within field device 14 and memory 60 is usedto store information. Memory 60 can comprise both permanent and volatilememory and can be used to store data used during processing, programminginstructions, calibration information, or other information, data orinstructions for use with process device 14. Memory 60 also storesinformation from sensor 74 as described herein.

FIG. 3 also illustrates ambient environment sensor 74 in accordance withone example embodiment. Ambient environment sensor 74 operates asdiscussed below in more detail and is configured to sense some aspect ofan ambient environment 75 of the field device 14. For example, ambientenvironment sensor 74 may comprise an image capture device. In such aconfiguration, sensor 74 is configured to capture images from theambient environment 75. Similarly, ambient environment sensor maycomprise an acoustic or ultrasonic sensor configured to capture acousticor ultrasonic signals from environment 75. In another example, sensor 74is a thermal detector configured to capture a thermal image such as aninfrared (IR) image. from environment 75. In one configuration, anoptional high resolution sensor 74A is provided. In such aconfiguration, sensor 74A can be used to capture high resolution imagesor sample the environment at a higher data rate than sensor 74.

As discussed above, the device 14 operates in a “pilot mode” obtaininglow resolution/data rate information from sensor 74 during normaloperation. A wide area of environment 75 can be monitored by sensor 74.For example, if sensor 74 is an infrared sensor, sensor 74 can comprisea low power infrared camera which is energized periodically to capturelow resolution images such as that shown in FIG. 4. Controller 34analyzes the low resolution images captured by sensor 74 to determine ifthere are thermal anomalies present that warrant capture of additionalhigh resolution images and analysis. This determination can be throughany appropriate technique, for example, a simple pixel comparison of thecaptured image to a reference image stored in the memory 60 of device14. This reference image can be captured during commissioning of thedevice, or based upon an input received through circuitry 32 or localinput 54. In another example, the reference image is transmitted to thedevice 14 using wireless communication or the like. The system maycontain several reference images in memory 60 which all depict normalthermal profiles for the specific field of view of the sensor 74. If theacquired image is found to match one of the “normal” images, or foundthrough some other low energy analysis technique to have no thermalanomalies present, the system may enter into a stand-by mode until thenext scheduled low resolution image is captured. However, if thecontroller 34 determines that the low resolution capture contains aprobable thermal anomaly such as illustrated in FIG. 5, the system mayenter a high resolution mode. In one configuration, in the highresolution mode, the sensor 74 enters a high resolution capture mode. Inanother example embodiment, a second, high resolution sensor 74A is usedto capture high resolution images. In this mode, field device 14collects one or more high resolution images of the particular field ofview of environment 75 such as illustrated in FIG. 6. These images canthen be further analyzed in order to provide additional characterizationof the anomaly including, for example, the location of the anomaly andtemperature. Further, the high resolution image may be transmitted to aremote location such as control room 12 for further analysis and may beviewed by an operator.

A similar technique can be used for an acoustic monitoring system. Forexample, a low power pilot mode can be used to acquire acoustic datafrom the environment 75 at a low sample rate using sensor 74. The lowsample rate data can be quickly analyzed in any appropriate way,including comparison of the low sample rate data to known normalacoustic profiles of the area stored in the memory 60 of device 14. FIG.7 is a graph of such low sampling data. This low spectral resolutionacoustic data shows an anomaly as illustrated in FIG. 7. When an anomalyis detected during the pilot mode, the controller 34 causes the systemto enter a high sampling rate mode to acquire a high band width acousticprofile of the environment such as illustrated in FIG. 8. This data maybe acquired using the same sensor 74, or may be acquired using adifferent sensor 74A configured for high data rate acquisition. Afterthe high data rate data is obtained, the profile can be characterized.For example, the profile can be scaled and compared to known acousticevents such as leaks, bearing wear, fires, etc.

FIG. 9 is a graph illustrating one technique for detecting an anomaly inan acoustic signal. FIG. 9 is a graph of amplitude versus frequency.Graph 80 illustrates a historical background or boundary “fence” ofsensed acoustic signals. This fence is one example of a stored profile.This may be programmed through a learning technique, or by an operatorsetting particular frequencies and thresholds. FIG. 9 also illustrates areceived acoustic signal 82 which violates the acoustic fence 80. Thisindicates that an anomaly has occurred in the received acoustic signaland can trigger a high resolution capture mode. Similar techniques canbe used for RF or other sensing technologies.

In addition to obtaining high resolution data or data at a higher samplerate, the field device 14 can operate at a high clock speed, forexample, by adjusting clock 62. This allows controller 34 to operate ata higher speed to analyze the collected data. In one aspect, the systemis configured to transmit information, for example, wirelessly usingcommunication link 28, which indicates that the power available frombattery 38 is insufficient for continued operation. For example,although the system is capable of continued “pilot mode” operation, thestored energy may be insufficient for the device to enter a high powermode for any significant period of time. When in this condition, thesystem may automatically transition into an alternate operating mode.Instead of entering a high spectral resolution mode when triggered, thesystem will omit this step and simply alert the user via the wirelessnetwork that an uncharacterized anomaly has been detected.

An anomaly may be detected using an appropriate technique. As discussedabove, the collected data can be compared to known normal profiles.Other techniques include comparison of the collected data to thresholdsin the time or frequency domain, monitoring for rapid changes or spikesin the collected data, monitoring for sudden drop outs in the collecteddata. The analysis may be done in the time or frequency domain, or somecombination thereof. As used herein, the term “ambient environmentsensor” refers to a sensor which is configured to sense an aspect of theambient environment of the device 14. These may be image sensorsincluding visible and infrared radiation, as well as acoustic sensorsincluding both audible and ultrasonic acoustic sensors. In oneconfiguration, the ambient environment sensor senses more than just asingle data point, for example, such as a single data point provided bya temperature sensor. The particular sensor may be configured to operatein two modes of operation, a low power “pilot mode” for acquiring lowresolution and/or low data rate information, as well as a high powermode for acquiring high resolution and/or high data rate information. Inanother configuration, a second ambient environment sensor is providedfor high resolution/data rate data collection. In another exampleconfiguration, one or more devices 14 are provided for monitoring anenvironment in the “pilot mode.” Data collected during the “pilot mode”monitoring is transmitted to another location, for example, overcommunication link 28. This information may be received at a locationwhich has a larger power source or is coupled to line power. The datacan be used to trigger a high power mode in which high data rate/highresolution data collection from a sensor at the remote location. Inanother example configuration, the anomaly may be detected in one device14, and a second device, such as device 16 shown in FIG. 1, used tocollect the high data rate/high resolution information. Similarly, ifthe sensor 74 is directional, when entering a high data acquisitionstate, the sensor may be aimed or “zoomed” into the area in which theanomaly was detected. Similarly, the sensor 74 may be configured to scanan area either in the “pilot mode” as well as in the high data ratemode.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. As used herein, the ambient environmentsensors preferably are configured to provide an output having a profile.The profile may be a plurality of pixels such as those which are used toan image, a plurality of amplitude or magnitude values such as from thesampled output of an acoustic sensor, or can be spectral content such asfrom an acoustic or image sensor. In the high power mode, the clock 62can operate at a higher frequency such that controller 34 operates afaster processing rate. As used herein, the term “anomaly” includes anactual anomaly, an impending anomaly as well as a probably anomaly. Aprobable anomaly includes an anomaly which is more likely than not tohave occurred. However, the threshold for what constitutes “probable”can be selected as desired.

What is claimed is:
 1. A wireless industrial process monitor formonitoring an industrial process, comprising: a controller configured tocontrol operation of the industrial process monitor; an ambientenvironment sensor configured to sense an ambient environment of theindustrial process proximate the process monitor and responsivelyprovide a sensor output signal, wherein the ambient environment sensoris configured to operate in a low power pilot mode and in a high powermode; wireless output circuitry configured to provide an output basedupon the sensor output signal; and wherein the controller causes theambient environment sensor to enter a high power mode upon detection ofan anomaly in the sensor output signal.
 2. The wireless industrialprocess monitor of claim 1 including a clock and wherein the clock isconfigured to provide a higher clock rate during the high power mode. 3.The wireless industrial process monitor of claim 1 including an internalpower source configured to power the wireless industrial processmonitor.
 4. The wireless industrial process monitor of claim 1 whereinthe ambient environment sensor comprises an image capture deviceconfigured to capture an image from the ambient environment.
 5. Thewireless industrial process monitor of claim 4 wherein the image capturedevice is configured to capture a thermal image.
 6. The wirelessindustrial process monitor of claim 4 wherein the controller isconfigured to detect the anomaly based upon a comparison of pixelswithin a captured image.
 7. The wireless industrial process monitor ofclaim 6 including a memory and wherein the comparison of pixels is basedupon a reference image stored in the memory.
 8. The wireless industrialprocess monitor of claim 7 wherein the memory is configured to store aplurality of reference images.
 9. The wireless industrial processmonitor of claim 1 wherein the controller is configured to detect ananomaly based upon a spike in a portion of a profile of the sensoroutput signal.
 10. The wireless industrial process monitor of claim 1wherein the controller is configured to detect an anomaly based upon achange in the sensor output signal.
 11. The wireless industrial processmonitor of claim 1 wherein the ambient environment sensor comprises afirst ambient environment sensor configured to sense the ambientenvironment during the low power pilot mode of operation and a secondambient environment sensor configured to sense the environment duringthe high power mode.
 12. A wireless monitoring system including thewireless industrial process monitor of claim 1 and a remote devicehaving a second ambient environment sensor.
 13. The wireless industrialprocess monitor of claim 1 wherein the ambient environment sensorcomprises an acoustic sensor.
 14. The wireless industrial processmonitor of claim 1 wherein the acoustic sensor comprises an ultrasonicsensor.
 15. The wireless industrial process monitor of claim 1 whereinthe controller is configured to detect an anomaly based upon a timedomain profile of the sensor output signal.
 16. The wireless industrialprocess monitor of claim 1 wherein the controller is configured todetect an anomaly based upon a frequency domain profile of the sensoroutput signal.
 17. The wireless industrial process monitor of claim 1wherein the ambient environment sensor enters a high resolution modewhen in the high power mode.
 18. The wireless industrial process monitorof claim 1 wherein the ambient environment sensor is directional and isconfigured to be aimed at the anomaly in the high power mode.
 19. Thewireless industrial process monitor of claim 1 wherein the ambientenvironment sensor comprises an image sensor and wherein a sensed imageis enlarged in the high power mode.
 20. The wireless industrial processmonitor of claim 1 wherein the ambient environment sensor is configuredto operate at a high data rate in the high power mode.
 21. A method in awireless field device in an industrial process control system formonitoring an industrial process, comprising: sensing an ambientenvironment of the industrial process using an ambient environmentsensor operating in a low power pilot mode; comparing an output from theambient environment sensor; detecting an anomaly in the sensor outputsignal based upon the comparing; and entering a high power mode inresponse to detection of the anomaly.
 22. The method of claim 21 whereinthe comparing is to a stored profile.
 23. The method of claim 21 whereinthe comparing is performed in the frequency domain.
 24. The method ofclaim 21 wherein the comparing is performed in the time domain.
 25. Themethod of claim 21 wherein the ambient environment sensor comprises animage sensor.
 26. The method of claim 21 wherein the ambient environmentsensor comprises an acoustic sensor.
 27. The method of claim 21including outputting an alert if there is insufficient power availableto enter the high power mode.
 28. The method of claim 21 wherein theambient environment sensor is configured to operate at a high data rateand/or high resolution in the high power mode.